
*** relative ***

In this example, relative homology of a pair of sets (X, Y) painted in 
a BMP file is computed. The set Y consists of black pixels, and the set 
X\Y is painted in grey.

In the first stage two cubical sets are extracted from the BMP picture: 
These are X and Y. Then we run the "homcubes" program to compute the 
relative homology of the pair.

Note: You can paint your own picture of another pair (X, Y), save it to the 
file "relative.bmp", and then run this example to compute its homology.
